taittreya upanishad - tradition of yoga and Upanishads, this concept of pancha kosha is described in Taittiriya Upanishad

In his search towards reality or the unchanging fundamental unit of this universe, a scientist started with the external gross world of solid matter which is simple and easy to see, divide, and do experiments with.
This search led him through steps of understanding of this entire world of matter starting from elements, molecules, atoms, protons, neutrons and electrons;
He further understood that it is all packets of energy.
The atoms conglomerate together to form various chemicals; our body is therefore a permutation and combination of various chemicals. (Packets of energy in various configurations) When they join together they form molecules, cells, tissues organs, etc.
These follow certain well defined laws of nature and are controlled by nervous (electrical) and chemical (hormones) mechanisms to bring about movement and action in each and every cell.
Thus annamaya kosha is the physical frame which the grossest of the five Koshas.

1. UPANISAD (ESSENCE OF KNOWLEDGE)

2. 5. Upanisad(essence of knowledge) 5.1. Introduction The Upanishads constitute the end part of the four Vedas namely the Rigveda, Yajurveda, Samaveda and Atharvaveda. Hence, they are also known as Vedanta, meaning the end of the Vedas (Veda + Anta).  The meaning of the word Upanishad Two possible, traditional meanings have been ascribed to the word Upanishad. According to the first, Upanishad (upa+ni+sad) means sitting near or down. It refers to the way the Upanishads were taught to the students in ancient India. Since the knowledge was taught to students who sat near the master, at a lower level or at his feet, while the master sat on a higher seat (asana), his teaching was called Upanishad.   

3. Essence of Upanisad Upanishad means the knowledge which destroys the bonds of ignorance and leads to liberation. The knowledge of the Upanishads is essentially the knowledge of Supreme Self (Brahman) and the individual Self (Atman). Knowledge of these two eternal realities is considered true knowledge or pure knowledge (sat), in contrast to the worldly knowledge (asat) which is temporary and which leads to ignorance, delusion and bondage to the cycle of births and deaths. Since the knowledge of the Upanishads destroys ignorance, it is considered liberating knowledge. Mahavakyas such as aham brahmasmi (I am Brahman), prajnanam brahma (Brahman is intelligence), tat tvam asi (you are that).

4. 5.4. Taittiriya Upanisad 1. Annamaya Kosha In the tradition of yoga and Upanishads, this concept of pancha kosha is described in Taittiriya Upanishad where in the teacher Varuna the father is guiding the student Bhrugu in his search for reality. The son asks the father to tell him about the most fundamental stuff of this universe from which all creation has come.

5. The father leads him on through hints to perform Tapas (internal research) to find out and experiential answer to the question. The son goes into silence and comes back to the father with an answer that this entire universe is made of ‘Anna’ (matter). Everything in the universe is sustained by Anna and everything dissolves into Anna. Father is very happy that the son has been able to arrive at one common principle of the external universe. This matter (Anna) based aspect of our physical personality is called Annmaya Kosha. Annamaya Kosha consists of five elements ( Pancha Bhutas) namely earth (Prithvi), water(Jala or Apa),fire (Agni or Tejas), wind (Vayu) and space (Akash) . This is normally nourished by the gross food that we consume. This is what the modern science also has understood. It has successfully unraveled the subtleties of this Kosha.

6. In his search towards reality or the unchanging fundamental unit of this universe, a scientist started with the external gross world of solid matter which is simple and easy to see, divide, and do experiments with. This search led him through steps of understanding of this entire world of matter starting from elements, molecules, atoms, protons, neutrons and electrons; He further understood that it is all packets of energy. The atoms conglomerate together to form various chemicals; our body is therefore a permutation and combination of various chemicals. (Packets of energy in various configurations) When they join together they form molecules, cells, tissues organs, etc. These follow certain well defined laws of nature and are controlled by nervous (electrical) and chemical (hormones) mechanisms to bring about movement and action in each and every cell. Thus annamaya kosha is the physical frame which the grossest of the five Koshas.

7. 2 . Pranamaya kosha Further Varuna sys ‘ my dear son there is something more subtle than what you have discovered, please go on and carry on with your research ‘. Bhrugu after a long research comes back and says ‘Oh Father it is the prana – the life energy, from which even the gross annamaya Kosha comes out. Prana the life energy described here is not the material electromagnetic energy spectrum known to modern science. All these energies like electricity, sound, light, radio, x-ray etc. belong to annamaya kosha as they are bound by energy laws. The prana described here is subtler than that. It does not follow the laws of the usual energies. It is described as – Syameva taanavam yaati, Svayameva pinataam yaati.’ That which can increase or decrease by itself without external agency. The body may be there but without life or Prana, it is gross useless.

8. This Prana is the basic fabric of this universe both inside and outside our body. A uniform harmonious flow of Prana to each and every cell of the annamaya kosha keeps them alive and healthy. Prana has the capacity to move into different areas of the body ( annamaya kosha) depending on demand. For eg. When you perform more brain work you need more prana in the head region. When you walk you need more prana in the lower limbs etc. If the prana flow to any organ increases inadvertently and without control, it can lead to dysfunction of that organ at the annamaya kosha. Prana flows through subtle channels called Nadis. The five dimensions of this mukhya prana flow resulting in activities in these areas are called Pancha Prana. The down ward force called ‘Apana’ is responsible for functions like defaecation, urination, menustration, ejaculation, parturition etc.

9. The prana responsible for breathing movement is called ‘Prana’. Udana is responsible for upward activities like vomiting; ‘Samana’ is responsible for proper digestion and balancing prana and apana. Vyana is that which is responsible for all activities in the periphery like nerves impulses, blood circulation, and cellular activity in all cells. A balance between all these five prana is health and imbalance is health. 3. Manomaya Kosha Bhirugu is now guided by his father to go back for Tapas. He returns after long penance and says ‘Oh my Guru, I realize that Manas (mind) is the source of everything’. This is called manomaya kosha. This is the aspect of one’s personality wherein the mind carries on its different functions such as perception (Manah), memory (chittah), and ego (Ahankara).

10. Mind, which is defined as a conglomeration of thoughts responds to the input through sense organs. For example, you see a big red flower; eyes send the image to the brain and the mind (manah) perceives it as a beautiful rose. Within the next fraction of a second your memory (Citta) deciphers that it as a very rare variety of rose which you wanted to see badly. The thought circulates in mind and citta which soon goes on to make you feel ‘O it is so beautiful! I like it, I love it, I want it!’ this component of the manomaya kosha in which this rapid recycling takes place and gathers momentum is called the ‘Emotions (Bhavana). This is characterized by feelings such as ‘likes or dislikes’, ‘love or hate’, backed by the heavy ‘I’ (the ego). It is this emotion that is the root cause of all human joy & distress. When the emotions become powerful, they start governing our actions against what is right. This ‘going against cosmic laws’ leads to imbalances called Adhi or Stress.

11. Long standing Adhis get pushed into pranamaya and annamaya kosha causing Vyadhis. Manomaya kosha is our mental and emotional library, the subtler layer of our existence. Hence the statement ‘you are what you think you are’ which Bhrugu realized as the basis of not only his own individual but also as the basis of the entire creation. 4. Vignanamaya Kosha As Bhirugu reports to Varuna about this wonderful discovery, the master is happy but he says ‘Please move on you have just a few steps to go ahead, you are in the right direction.’ Now through intense long tapas, Bhrugu realizes that it is all the Vijanana (knowledge) from which the entire creation has happened and that could be the final reality. Vijananamaya Kosha is the fourth layer of our existence. We all have two minds.

12. E.g. when the manomaya kosha said that ‘ It is a beautiful rose, I want to have it’ and you started instructing your hands to pick up the flower, inner mind said ‘ Sorry, you cannot pluck that flower; it does not belong to you; it is from the neighbour’s garden and you stopped the action. This conscience within that continuously guides us to do a thing or not to do a thing is the Vijanana maya kosha. It is this component of the mind that has developed in human race greatly that differentiates man from animals. Bharthruhari says, “ Ahara nidra bhaya maithunan cha Samaanyametat pashubhih naraanam Bhuddhirhi tesam adhiko visheshah Buddhirvihinah pashubhih samanah”   Hunger, sleep, fear, procreative instinct are common to man and animals.

13. It is the Buddhi (discriminating faculty) that is special for man. A person who does not have Buddhi is equal to an animal. Bhartruhari brings out this point as to how the higher faculty the Vijananamaya continuously guides the manomaya kosha to get mastery over the basic instincts. Hence in man we know that even these basic instincts are all psychological. For example we have lost the cyclical behavior as in animals who get into reflex estrus cycles ( heat for sexual behavior) . This freedom element which is inbuilt in all human beings, guides him to discriminate what is ‘good & bad’ , ‘right & wrong’, ‘useful & not useful’ to move towards long term sukha ( happiness). Thus vijananamaya kosha is the discriminating faculty.

14. 5. Anandamaya Kosha Varuna now directs the son to go back to tapas and this time Bhrugu never returns. The master goes to check why the son has not come back. He was surprised to see that Brugu is completely engrossed in deep Ananda (bliss). There is no individual ‘I of the vijanana or manomaya that can report to the father about his realization. Bhrugu is now established in the knowledge of the final truth that Ananda is the basic stuff of this universe from which every thing has been created. This is called anandamaya kosha – the bliss layer of our existence. This is the most subtle aspect of our existence which is devoid of any form of emotions; a state a total silence – a state of complete harmony and perfect health. While in manomaya kosha the creative power predominates, in Vijananamaya kosha it is the power to discern and discriminate. .

15. Bliss is embodied in Anandamaya kosha, the highest stage of evolution in the manifested existence In his journey towards the Ultimate, man crosses these koshas of existence one by one. Through analysis called ‘Pancha Kosha Viveka’ ( knowing through experience, one’s five koshas of existence) and the associated practices called ‘tapas’ man transforms himself gradually getting relieved from the bondages and constrictions of each kosha. This is one of the methods of reaching the ultimate goal enumerated and described in Upanishads.